Method of production of graphite oxide and uses thereof

Abstract

The present invention is related to a new scalable method of forming graphite oxide (only one or few layers of carbon atoms) of high purity (notably without metallic residues) and high oxidation degree from graphite flakes in a cost-effective and reduced environmental impact.

What is claimed is: 
     
       1. A method of forming graphite oxide comprising:
 a) adding intercalated flakes of graphite in a reaction vessel; 
 b) adding nitric acid to the intercalated graphite flakes in the reaction vessel at a temperature around 0° C. to obtain a mixture; 
 c) adding a chlorate salt as an oxidant to the mixture, while stirring and controlling the formation of ClO 2  such that it does not exceed about 10% v/v; 
 d) increasing the reaction temperature at a rate of about 3 to 5° C/h to room temperature over about 12 hours to form graphite oxide; and 
 e) washing and separating the graphite oxide from the reaction mixture to give an isolated graphite oxide; 
 wherein b) to d) are conducted under an air purge, while stirring. 
 
     
     
       2. The method according to  claim 1 , wherein the flakes of graphite have a flake size of about 180 μm to about 350 μm. 
     
     
       3. The method according to  claim 1 , wherein the flakes of graphite are selected from sulphate and perchlorate intercalated flakes of graphite. 
     
     
       4. The method according to  claim 1 , wherein the flakes of graphite are sulphate intercalated flakes of graphite. 
     
     
       5. The method according to  claim 1 , wherein the chlorate salt is sodium chlorate. 
     
     
       6. The method according to  claim 1 , wherein the controlling of the formation of ClO 2  is such that its level in the reactor does not exceed about 10% v/v is carried out by adding the oxidant in portions or by dosing the addition of the oxidant. 
     
     
       7. The method according to  claim 1 , further comprising, during and/or at the end of d):
 d1) adding a further nitric acid amount to ensure sufficient mixing of the mixture. 
 
     
     
       8. The method according to  claim 1 , further comprising, after d) and before e):
 d2) warming the reaction mixture up to about 60° C. in 1hour or more and stabilizing the temperature for about 30 minutes; and 
 d3) cooling the reaction mixture to a temperature of about 0° C. and adding ice. 
 
     
     
       9. The method according to  claim 1 , wherein the stirring is mechanical stirring. 
     
     
       10. The method according to  claim 1 , wherein the washing and separation e) comprises the following:
 e1) adding water to the mixture obtained under d) and optionally stirring; and either 
 e2i) allowing to decant and optionally sucking out the supernatant; or 
 e2j) filtering the mixture; 
 wherein e1 ) and e21) or e1) and e2j) are repeated until a neutral pH for the mixture is reached. 
 
     
     
       11. The method according to  claim 1 , wherein isolated graphite oxide is obtained under e) after an optional centrifugation of the reaction mixture resulting from the last washing and/or filtration. 
     
     
       12. The method according to  claim 1 , further comprising g) adding deionized water to the isolated graphite oxide flakes obtained under e) and lyophilizing the mixture. 
     
     
       13. The method according to  claim 1 , wherein the C/O atomic ratio of the graphite oxide obtained is between about 2.7 and about 3.2. 
     
     
       14. The method according to  claim 1 , wherein the graphite oxide has a flake size of about 180 μm to about 350 μm, and an oxidation degree<or equal to about 3. 
     
     
       15. A method of preparing graphene, comprising:
 a) adding intercalated flakes of graphite in a reaction vessel; 
 b) adding nitric acid to the intercalated graphite flakes in the reaction vessel at a temperature around 0° C. to obtain a mixture; 
 c) adding a chlorate salt as an oxidant to the mixture, while stirring and controlling the formation of ClO 2  such that it does not exceed about10% v/v; 
 d) increasing the reaction temperature at a rate of about 3 to 5° C./h to room temperature over about 12 hours to form graphite oxide; 
 e) washing and separating the graphite oxide from the reaction mixture to give an isolated graphite oxide; and 
 subjecting the graphite oxide to ultrasonication to obtain graphene, 
 wherein b) to d) are conducted under an air purge, while stirring. 
 
     
     
       16. A method of preparing graphene, comprising:
 a) adding intercalated flakes of graphite in a reaction vessel; 
 b) adding nitric acid to the intercalated graphite flakes in the reaction vessel at a temperature around 0° C. to obtain a mixture; 
 c) adding a chlorate salt as an oxidant to the mixture, while stirring and controlling the formation of ClO 2  such that it does not exceed about 10% v/v; 
 d) increasing the reaction temperature at a rate of about 3 to 5° C./h to room temperature over about 12 hours to form graphite oxide; 
 e) washing and separating the graphite oxide from the reaction mixture to give an isolated graphite oxide having a flake size of about 180 μm to about 350 μm, and having an oxidation degree<or equal to about 3; and 
 subjecting the graphite oxide to ultrasonication to obtain graphene, 
 wherein b) to d) are conducted under an air purge, while stirring. 
 
     
     
       17. The method according to  claim 8 , wherein the C/O atomic ratio of the graphite oxide is between about 2.7 and about 3.2. 
     
     
       18. The method according to  claim 8 , wherein the graphite oxide has a flake size of about 180 μm to about 350 μm, and an oxidation degree<or equal to about 3.